Recently especially in United States, the needs is rapidly increasing for a plastic lens using a polycarbonate resin of transparent and having excellent impact resistance, for the use of the sunglasses with a dizziness prevention property. Further, in regards with such plastic sunglass, the photochromic sunglass made of plastic (a photochromic lens) is rapidly becoming popular which can control the dizziness prevention property by changing a transparency depending on the surrounding brightness by including a photochromic compound.
The photochromic lens is manufactured with various methods. In concrete, a method, wherein a coating composition including a photochromic compound is coated on the surface of plastic lens, and a method, wherein the photochromic compound is mixed in a material of plastic lens itself and lens is formed, can be exemplified.
Further, the following method is now being examined considering that it can be partly processed, it is possible to form a smooth photochromic layer, and it is possible to provide photochromic properties at the time when manufacturing a plastic lens by an injection molding. Namely, it is a method to use a photochromic adhesive agent (a photochromic composition) including a photochromic compound and a polyurethane resin. In concrete, “a photochromic laminated article”, wherein optical sheets such as polycarbonate resins are mutually bound by said photochromic adhesive agent, is manufactured at first, subsequently, said laminated article is installed in a metal mold for a lens forming, and then an injection molding or a thermocompression is performed. With this method, a photochromic lens having the laminated article can be manufactured (See Patent Articles 1 to 4). Thus obtained photochromic lens binds the laminated article and a plastic lens by an injection molding or a thermocompression. Therefore, an adhesion between an interface of the laminated article and the lens becomes extremely high.
On the other hand, with the methods described in patent articles 3 and 4, However, there was a problem of releasing optical sheets due to an insufficient adhesion between the optical sheets and the photochromic adhesive agent, when using the optical articles manufactured with the above patent articles 1 and 2. This may be due to a structure of the polyurethane resin, which is a main component of an adhesive agent (There was a case wherein optical sheets are released due to an insufficient adhesion of a photochromic laminated article itself.). In addition, there was a problem of generating an optical strain or so when performing an injection molding or a thermocompression, due to an insufficient heat resistance of the polyurethane resin. Therefore, it is required to improve heat resistance of a matrix resin (a polyurethane resin) itself of a layer comprising the adhesive agent.
However, the polyurethane resin of 2 liquid type (a mixture of a compound having an isocyanate group at a terminal end and a compound having a hydroxyl group at a terminal end) is used in the methods described in patent articles 3 and 4. This is a method to form a high-molecular-weight urethane resin layer (an adhesive agent layer) by laminating a composition including the polyurethane resin of 2 liquid type and the photochromic compound on an optical sheet, and then by making the polyurethane resin of 2 liquid type to react. Said composition before the lamination has a relatively low molecular compound; and that with this method, there is an advantage of not lowering the solubility of the composition itself and the same of the photochromic compound. In addition, the polyurethane resin of 2 liquid type is made to react to make a high-molecular-weight a polyurethane resin after the lamination; thus its heat resistance can also be improved.
However, even with the photochromic adhesive agent obtained by the above method, an adhesion of the photochromic laminated article itself was insufficient; and that a problem of releasing the optical sheets was unable to be sufficiently solved. The photochromic lens may contact high humidity or warm water when used in everyday life. And that an adhesion between optical sheets and an adhesive agent must be high even under such circumstances. Namely, optical sheets are desired to firmly bind even when the photochromic laminated article itself is under such circumstances. With the photochromic adhesive agent obtained from the reacted polyurethane resin of 2 liquid type, it was difficult to maintain a high adhesion between optical sheets and the adhesive agent after contacting with warm water and the like, while maintaining a high photochromic properties; and there was a room for an improvement.
Further, besides the above injection molding or thermocompression, the following method is suggested as a manufacturing method of the photochromic lens using “a photochromic laminated article”. In concrete, it is a method wherein a photochromic lens is formed by polymerizing and cuing a polymerizable monomer after immersing the photochromic laminated article in said polymerizable monomer (See Patent Articles 4 and 5). With this method, capabilities of the obtained lens can be easily changed by changing a kind of polymerizable monomer; and that lens provided with various capabilities can be manufactured. Further, a photochromic lens can be manufactured at a relatively low temperature when compared to an injection molding or thermocompression; and that strain of lens due to a heat can be reduced.
However, there was a room for an improvement considering the following points when a method described in patent articles 5 and 6 were used. Patent articles 5 and 6 suggest a use of a thermosetting polyurethane resin of 2 liquid type, comprising polyurethane prepolymer and curing agent, as a photochromic adhesive agent. When a thermosetting polyurethane resin described in patent articles 5 and 6 are used, there was a case when a thermosetting polyurethane resin or a photochromic compound is dissolved from a photochromic laminated article in a polymerizable monomer depending on a kind of a polymerizable monomer or a polymerization condition. This elution generates at an end part of a photochromic laminated article. This end part, wherein the photochromic laminated article eluted, is required to be removed from lens. Thus, an effective area of lens became small as this elution part became small; and there was a room for an improvement. Further, when said eluted part is removed from lens, an end face of a photochromic laminated article exists on the same surface with the same of a photochromic lens; and that an adhesion of the thermosetting polyurethane resin may be insufficient and there was a possibility of releasing lens.    [Patent 1] US Patent Application Laid Open No 2004096666    [Patent 2] JP Patent Application Laid Open No. 2003-519398    [Patent 3] US Patent Application Laid Open No 20050233153    [Patent 4] US Patent Application Laid Open No 20020006505    [Patent 5] JP Patent Application Laid Open No. 2005-181426    [Patent 6] JP Patent Application Laid Open No. 2005-215640